Bayer's Stivarga Shows Slim Progress Against Liver Cancer

Today the FDA approved a new drug—one of few available—for treating liver cancer. Regorafenib is a pill manufactured by Bayer and sold as Stivarga. Already it’s been approved for use in some patients with refractory colon, rectal, and GI stromal tumors.

While I think this generally good news for affected patients, my enthusiasm is tempered by the poor response rate, and by its toxicity. The FDA based its approval on results from a randomized trial of 573 patients with progressive hepatocellular (liver) cancer.

As reported by the FDA, overall survival for liver cancer patients receiving Stivarga was 10.6 months, as opposed to 7.8 months with placebo. I wouldn’t dismiss that small difference, of 3 months, if the disease were more tempered by this drug in more of the patients who tried it. But progression free survival (PFS) was only 3.1 months for those liver cancer patients taking Stivarga, vs. 1.5 months with placebo – an almost negligible difference. Meanwhile side effects were serious and common, as described, including pain, rashes, fatigue, nausea, diarrhea, liver failure, hypertension and other cardiovascular problems, infection, you name it.

Liver cancer represents an increasingly common tumor in the U.S. and around the globe. The incidence of liver cancer has more than tripled since 1980, the ACS reports. The disease tends to strike in late middle-age, but affects people in all generations, of all races, and men more than women. Chronic inflammation due to hepatitis B or C is implicated as a cause in many but not all cases. The IARC reports that liver cancer is the second most common cause of cancer deaths worldwide; around 750,000 people receive a diagnosis each year, and it’s usually lethal.

According to the NCI’s website today, fewer than 80% of patients reach the 5-year survival mark. (I suspect that statistic, from 2009, is outdated, but the point remains.) There’s a desperate need for better ways to treat liver cancer, but this drug doesn’t approach the level of improvement that should be available, soon.

This drug (Regorafenib, BAY-73-4506) is said by investigators at Bayer to be a broad inhibitor of cellular enzymes (proteins, called kinases). Unlike precision medicines, which at least in principle are designed to match a single or few molecular targets, this agent is not specific in its activity; it can affect many signals in cancerous and healthy cells. That is probably why it’s comparatively toxic.

Of interest, you can buy a 1-month supply of this drug for around $5,500, which is lower than the cost of most new anti-cancer agents (typically $12,000 per month for pills). Stivarga may cost less because doctors and patients have had bad experiences in terms of toxicity and treatment failures. Surely Bayer can do better than this.

National Cancer Institute

incidence of liver (and bile duct) tumors in the U.S. is rising (SEER data, from NCI website April 27, 2017)

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